1. Field of the Invention
The present invention relates to a writing method carrying out writing of a multi-layer circuit pattern or the like, and to a writing method using the writing device.
2. Description of the Related Art
In recent years, light modulating elements have been used in methods of fabricating multi-layer circuit patterns. In a specific method of fabricating a multi-layer circuit pattern, first, as shown in FIG. 17A, the surface of a printed board is copper plated. Thereafter, as shown in FIG. 17B, a photosensitive resin called a photoresist is coated thereon.
When light is irradiated on the photoresist, the photoresist hardens (although there are cases in which the photoresist softens when light is irradiated thereon). After the photoresist is exposed by light modulating elements as shown in FIG. 17C, when developing is carried out (see FIG. 17D), the exposed portions of the photoresist remain, and the other portions are rinsed off.
Then, as shown in FIG. 17E, the copper at the portions where the photoresist was rinsed off is etched by etching. Thereafter, as shown in FIG. 17F, the photoresist is peeled off. An insulating material is coated on the entire surface (see FIG. 17G).
Next, as shown in FIG. 17H, holes are formed by a laser at the portions where the top and bottom must be made continuous. Thereafter, as shown in FIG. 17I, copper plating is carried out. A photoresist is coated (see FIG. 17J).
Then, after the photoresist is exposed by light modulating elements as shown in FIG. 17K, developing is carried out (see FIG. 17L). In this way, the portions of the photoresist which were not exposed are rinsed off. As shown in FIG. 17M, etching is carried out such that the copper at the unexposed portions is etched.
Next, after the photoresist is peeled off as shown in FIG. 17N, an insulating material is coated by screen printing as shown in FIG. 17O. Here, hole portions are formed in advance in the screen printing. Solder is adhered within these hole portions, and electronic parts or the like are made continuous via the soldering.
Here, devices are provided separately for the process of coating a conductive material or an insulating material on the medium on which writing is carried out, and the process of exposing the photoresist. The medium on which writing is carried out is set on stages provided at the respective devices, and the respective processes are carried out. Thus, the medium on which writing is carried out must be set at a stage each time a process is to be carried out, and much time is required for the operation.
Moreover, because a device is provided independently for each process, positioning of the medium on which writing is carried out must be carried out each time a process is to be carried out. When a laminated pattern is to be formed, there are cases in which positional offset of the pattern arises.
On the other hand, as shown in FIGS. 18A and 18B, by using a silver salt photosensitive material which forms different colors when exposed at three wavelengths (e.g., R, G, B), black is exposed by UV (405 nm), red is exposed by B (450 nm) and G (532 nm), green is exposed by B (450 nm) and R (635 nm), and blue is exposed by G (532 nm) and R (635 nm) by using an exposure device having four exposure heads (R, G, B, UV). After exposure, when the photosensitive material passes through a developing liquid and is developed, in the case in which the photosensitive material is a web, all of the colors are formed simultaneously, and patterns of the respective colors are formed. However, in order to obtain high-density coloring, the thickness of the photosensitive material must be several tens of μ m, and the accuracy of pattern formation has been insufficient.